A process for adhering a resin molded article to a rubber molded article by an adhesive is known as a process of adhering a resin molded element to a rubber molded element. However, the process using the adhesives complicates the process to cause a troublesome process-control, and not only costs a lot but also does not necessarily give a sufficient adhesive strength.
Meanwhile, a composite of a resin directly bonded to a rubber has been proposed. For example, Japanese Patent Application Laid-Open No. 25682/1975 (JP-50-25682A) discloses a process for producing a rubber-plastic composite, which comprises rubbing a thermoplastic plastic component (e.g., a polyformaldehyde and an olefinic polymer) and a vulcanized rubber component (e.g., polybutadiene, and nitrile) compatible with the thermoplastic plastic component with contacting each other to melt or fuse the surface of the plastic, and solidifying the melted surface of the resin with contacting the thermoplastic resin component and the vulcanized rubber component. However, in the process, since a configuration of the bonding site or position in the composite is restricted, it is difficult to produce a composite of a thermoplastic resin molded article and a rubber molded article, each having a complicated configuration on a bonding site, and to increase the productivity of the composite.
Regarding a polyphenylene ether-rubber composite, Japanese Patent Application Laid-Open No. 204260/1986 (JP-61-204260A) discloses a process for producing a composite, which comprises heating a polyphenylene ether-series resin which may have a styrenic polymer and/or an additive together with a synthetic rubber comprising SBR, BR, IR, IIR or the like in the presence of the vulcanizing system. With respect to an ABS resin-rubber composite, Japanese Patent Application Laid-Open No. 301973/1993 (JP-5-301973A) discloses a process for producing a composite, which comprises laminating an ABS resin molded member and an unvulcanized-rubber sheet composed of a rubber component having a critical surface tension of 37 to 39 mN/m, and subsequently heating the laminated sheet for adhering integrally. Japanese Patent Application Laid-Open No. 124803/1997 (JP-9-124803A) discloses a process for producing a composite member, which comprises heating an acrylonitrile-containing thermoplastic resin (e.g., AS resin, ABS resin) with an acrylonitrile-containing rubber with intimately contacting each other. However, these processes markedly restrict species of resins and rubbers for combination because the thermoplastic resin and the rubber are adhered by utilizing the compatibility for improving bondability (or adhesiveness) between the both components, and therefore the practical applications are much limited.
Referring to a polyamide-rubber composite, Japanese Patent Application Laid-Open No. 150439/1990 (JP-2-150439A), Japanese Patent Application Laid-Open No. 133631/1991 (JP-3-133631A) and Japanese Patent Application Laid-Open No. 138114/1991 (JP-3-138114A) disclose a process for producing a polyamide-rubber composite, which comprises vulcanizing or crosslinking a rubber component with contacting a polyamide-series resin in the presence of the vulcanizing agent, wherein the rubber component comprises a carboxyl group or an acid anhydride group-containing rubber, a peroxide, a vulcanization-activating agent (e.g., ethylene glycol dimethacrylate, and triallyl isocyanurate), and an alkoxysilane compound. Japanese Patent Application Laid-Open No. 156188/1996 (JP-8-156188A) discloses to obtain a composite member by vulcanizing or crosslinking a carboxyl group- or an acid anhydride group-containing rubber member with contacting closely an epoxy group-containing resin member. Since the processes described in these documents utilize a chemical reaction (a bonding reaction between an amino group and a carboxyl group or an acid anhydride group, a bonding reaction between an epoxy group and a carboxyl group) for adhering the resin and the rubber, a combination of species of resins and rubbers is markedly restricted, and therefore it is difficult to obtain a resin/rubber composite in a wide combination of the resin and the rubber.
Regarding a process for producing a polyester-rubber composite comprising a thermoplastic polyester as a hard component and a vulcanized rubber as a soft component, Japanese Patent Application Laid-Open No. 304880/1995 (JP-7-304880A) discloses a use of a rubber component comprising a rubber, a peroxide vulcanizing agent, a di- or poly-functional maleimide, and, if necessary, a vulcanization-activating agent, and Japanese Patent Application Laid-Open No. 166043/1995 (JP-7-166043A) proposes to use a rubber component comprising a rubber, a peroxide vulcanizing agent, a silane compound, and, if necessary, a vulcanization-activating agent. Further, concerning a composite film or sheet comprising a resin film and a rubber film, Japanese Patent Application Laid-Open No. 58605/1998 (JP-10-58605A) discloses a process for producing a composite film by laminating a rubber film (e.g., silicone rubber, ethylene-propylene-series rubber) comprising a polyfunctional methacrylate as an adhesion-improving agent on a substrate film (e.g., a polyester film), and vulcanizing or crosslinking the laminate. In these processes, while the vulcanization-activating agent is added to the rubber component for improvement of bondability (or adhesiveness), the combination of the resin and the rubber is restricted, and therefore a wide range of rubbers and resins cannot be integrally joined or bonded together with a high bonding strength (or adhesive strength).
It is therefore an object of the present invention to provide a resin composition in which a resin can be certainly and firmly joined (or bonded) to a wide range of rubbers without using an adhesive, and a process for producing the same.
Another object of the present invention is to provide a resin composition which ensures to stably and industrially produce a composite of a rubber and a resin firmly joined (or bonded) to the rubber, and a process for producing the same.
It is still another object of the present invention to provide a composite in which a resin and a rubber are directly joined (or bonded) together certainly and firmly, and a process for producing the same.